The advantages to learning exposure with digital are that it doesn't cost you any more to make more exposures (no film/development costs) and immediate feedback. You can instantly see the effect of setting change when you take the image (or if you're using a camera where you compose on the LCD or through an electronic viewfinder in liveview, before you take the shot with exposure simulation). In addition, each image you take will have embedded metadata that will let you check later on what iso, aperture, and shutter speed settings you used. Film doesn't dot that, and you have to keep notes, which can be awkward while you're shooting.

But on the flip side, film will give you shot discipline in mental editing quite a bit harder before you mash that button that digital spray'n'prayers may never learn. :) The main problem here with your AE-1 is that you may not know if it's working correctly or needs to be service as well as your skillset not yet being able to figure out where you might have gone wrong if the exposure isn't right.

But you don't necessarily have to use a digital camera if the film camera works fine (no light leaks, broken parts, etc.) it might be worth it for you to put a light metering app on your smartphone. Some of them do exposure simulation and if they match your AE-1's exposure, then maybe it's a way to have a preview first before you shoot.